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Measured wavenumber: Frequency spectrum associated with acoustic and aerodynamic wall pressure fluctuations
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View: Figures


Image of FIG. 1.
FIG. 1.

Wall pressure spectrum of a low Mach number turbulent boundary layer in the plane for a given frequency : (a) for , (b) for and (c) for .

Image of FIG. 2.
FIG. 2.

Sketch of the rotative measurement array, and picture showing the arrangement of the holes on the wall at one end.

Image of FIG. 3.
FIG. 3.

Auto-power spectral (APS) densities of wall pressure fluctuations measured by the three kinds of probes under a turbulent boundary layer at and . From bottom to top: — big probes, – – – medium probes and small probes.

Image of FIG. 4.
FIG. 4.

Test channel mounted on the outlet of the wind tunnel. The square duct has a width of and a test-section length of a 4 m. The rotating array of remote microphones is located at .

Image of FIG. 5.
FIG. 5.

Mean velocity profile (•) and turbulence intensity (▴) measured by hot wire anemometer in the boundary layer at . The transverse distance is normalized by the half-width of the channel, refer to Fig. 4.

Image of FIG. 6.
FIG. 6.

Verification test case for a pure tone diffuse sound field, with and . Profile of along the line , post-processing of the theoretical cross-power spectra in solid line, analytical expression given by Eq. (8) in dashed line.

Image of FIG. 7.
FIG. 7.

Verification test case for the Corcos model, with , , , and . Profile of along the line . The convected wave number is . — post-processing of the theoretical cross-power spectra, – – – analytical expression given by Eq. (10).

Image of FIG. 8.
FIG. 8.

Measured spectrum at in the wavenumber space induced by a turbulent boundary layer.

Image of FIG. 9.
FIG. 9.

Acoustical spectral density obtained by integration over the acoustic disk .

Image of FIG. 10.
FIG. 10.

Coherence function , see Eq. (11), in the longitudinal direction at . ● experimental data, – – – regression and linear regression.

Image of FIG. 11.
FIG. 11.

Computed parameters for the model (12). (a) Convection velocity normalized by the free stream velocity as a function of the frequency. (b) Longitudinal and transversal correlation lengths, in solid line and in dashed line respectively.

Image of FIG. 12.
FIG. 12.

Measured auto-power spectral (APS) density in solid line. Acoustic part estimated by integration of over the acoustic disk in dashed line, and acoustic part estimated by Corcos-like model (12) in dotted line.


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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Measured wavenumber: Frequency spectrum associated with acoustic and aerodynamic wall pressure fluctuations